Write two parts of fluid mechanics and what studies are made in them?

The heart of a man pumps $5 \, \text{litres}$ of blood through the arteries per minute at a pressure of $150 \, \text{mm}$ of mercury. If the density of mercury is $13.6 \times 10^3 \, \text{kg/m}^3$ and $g = 10 \, \text{m/s}^2$, then the power (in $\text{watt}$) is:

An air bubble of volume $1\,cm^3$ rises from the bottom of a lake $40\,m$ deep to the surface at a temperature of $12^{\circ}C$. The atmospheric pressure is $1 \times 10^5\,Pa$,the density of water is $1000\,kg/m^3$,and $g = 10\,m/s^2$. There is no difference in the temperature of water at the depth of $40\,m$ and on the surface. The volume of the air bubble when it reaches the surface will be $..........\,cm^3$. (in $,cm^3$)

Explain why:
$(a)$ To keep a piece of paper horizontal,you should blow over,not under,it.
$(b)$ When we try to close a water tap with our fingers,fast jets of water gush through the openings between our fingers.
$(c)$ The size of the needle of a syringe controls flow rate better than the thumb pressure exerted by a doctor while administering an injection.
$(d)$ $A$ fluid flowing out of a small hole in a vessel results in a backward thrust on the vessel.

At a speed of .......... $m/s$,the velocity head of water is equal to the pressure head of $40\, cm$ of $Hg$.

$A$ pump motor is used to deliver water at a certain rate from a given pipe. To obtain twice as much water from the same pipe in the same time, the power of the motor has to be increased to: (in $times$)